Focusing on the calf is the simple and straightforward take-home message for all dairy and beef producers when it comes to controlling Johne's disease in their herds.
This was the bottom-line conclusion of Michigan State University researchers and MSU Extension specialists after conducting field research and evaluating Johne's disease control strategies for close to a decade in Michigan herds as part of the Michigan Johne's Disease Control Demonstration Project. The objective of the work was to identify which management practices are the most effective at controlling the spread of Johne's disease.
Dr. Dan Grooms, veterinarian, Food Animal Division head in the MSU College of Veterinary Medicine and the lead researcher on the project, summarized the findings in four words: focus on the calf.
"It sounds too simple, but if we can simply reduce the risk of calves becoming exposed to the bacteria that causes Johne's disease, then we can make significant progress in reducing the impact of the disease on both dairy and beef operations," he says.
Johne's disease is a contagious and untreatable disease caused by the bacteria Mycobacterium paratuberculosis, or MAP. Though infection typically occurs in calves, animals generally don't express clinical signs of the disease until later in life.
He said the goals of the project were to evaluate the effectiveness of Johne's disease control strategies, develop new knowledge about control strategies through field research studies, develop education resources and promote the Michigan Voluntary Johne's Disease Control Program. The Michigan Department of Agriculture and Rural Development (MDARD) and the United States Department of Agriculture (USDA) Animal and Plant Health Inspection Service (APHIS) administer the Michigan Voluntary Johne's Disease Control Program.
The Michigan Johne's Disease Control Demonstration Project was a partnership between the MSU College of Veterinary Medicine, the MSU Diagnostic Center for Population and Animal Health, MSU Extension, the MDARD and the USDA in collaboration with nine Michigan veterinary clinics. Findings from the Michigan farms involved in the study were pooled with data collected from 17 other states as part of the larger, multi-state project, the National Johne's Disease Control Demonstration Project.
Nine herds – one beef operation and eight dairy herds – were enrolled in the Michigan project. Selected farms represented a variety of management styles and were located across the state. Farms were enrolled in the project between 2002 and 2005 and participated in the program for four to seven years.
Each herd underwent whole-herd testing to measure baseline levels of Johne's disease infection. From there, a disease risk assessment was conducted, and management practices were put in place to help control on-farm spread of the disease.
Each herd participating in the project tested positive for Johne's; the percentage of cows infected in each herd ranged from 6 percent to 14 percent.
"Each of the nine herds – like the majority of dairy and beef operations in the state – was infected with Johne's (Disease) at the time of enrollment," Grooms says. "At the end of the project, the farms had reduced the prevalence of Johne's disease in their herds and the number of cattle detected with clinical signs of the disease, and increased the overall herd health."
The disease was not eradicated from any of the herds during the project. MSU Extension educator Phil Durst, another primary researcher on the project, stressed that eradication is a long-term goal for producers and isn't something that can be achieved overnight.
"Modifying existing or adopting new management practices to reduce the potential for transmitting the disease must be permanent changes," he explained. "The number of animals that test positive for the disease may actually even increase for several years (when a control program is implemented) because infected animals are more likely to test positive later in life."
"When producers perform the recommended practices to reduce the risk of transmitting Johne's, they also help to reduce the animals' exposure to other diseases and lower their risk of catching them. In doing so, they increase the herds' overall health," he adds. "For all the producers participating in this project, these benefits were worth the cost and effort of implementing a Johne's disease control program in their herds."
And what was the most compelling piece of evidence collected by researchers supporting the recommendation to focus on calf management practices to reduce the incidence of Johne's disease?
"In every herd that participated in the project, significant changes were made to how the calves were managed, and the incidence of Johne's was reduced significantly," Grooms says. "By focusing resources and efforts on reducing MAP transmission from older animals to young calves, Johne's disease can be effectively managed and its impact reduced on farms."
Results from field-based research studies associated with the project have been reported at national and international meetings, published in peer-reviewed publications and shared with producers at MSU Extension meetings and field days at four of the project farms. They are also available in print form in the publication, "The Michigan Johne's Disease Control Demonstration Project: Research Findings, Lessons Learned, Producers' Perspectives." Download a copy of the project report at http://cvm.msu.edu/johnes, or contact Dr. Grooms at [email protected] for a copy.
MSU also has been involved in the USDA-funded multi-year, multi-state Johne's disease Integrated Project and hosted the first annual "New Horizons in Johne's Disease Control" workshop in 2008.
Grooms says that findings from this work will have a far-reaching and positive effect on the future of the beef and dairy industries.
"The program has – and will continue to – provide background for educating producers on the positive correlation between implementing effective management decisions to control Johne's Disease in their operations and the profitability of their businesses and overall improved animal welfare," he says.
Additional information on the Michigan Johne's Disease Control Demonstration Project can be found at http://cvm.msu.edu/johnes.